Pendulum



No. 753,475. PATBNTED MAR. 1, 1904.

J. W. DAILY.

PENDULUM.

APPLICATION FILED MAR. 23, 1903. K0 MODEL.

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Patented March 1, 1904.

PATENT OFFICE.

JOHN W. DAILY, OF BOSTON, MASSACHUSETTS.

PENDULUM.

SPECIFICATION forming part of Letters Patent No. 753,475, dated March 1,1904.

Application filed March 23, 1903- To all whom it may concern:

Be it known that I, J OHN W. DAILY, of Boston, county of Suffolk, andState of Massachusetts, have invented an Improvement in Pendulums, ofwhich the following description, in connection withthe accompanyingdrawing, is a specification, like letters on the drawing representinglike parts.

The present invention relates to a compensating pendulum forchronometers, and is embodied in a pendulum in which the pendulumrod andthe pendulum-bob are made of different materials having differentcoefficients of expansion, the rod being shown as of wood and the bob asof metal, the said bob being supported by the rod at its lower end, sothat as it expands its center of gravity will be raised with relation tothe pivotal axis of the rod to compensate for the increase in length ofthe rod due to the same influence of temperature.

It is the purpose of the present invention to construct the penduluminsuch a manner that a practically perfect adjustment can be made of therelation between the rod and the bob,

so as to obtain perfect compensation, without, however, varying theefiective length of the pendulum, which of course would make the clockrun faster or slower, as the case might be. To these ends the bob issupported upon adjusting-nuts threaded upon supporting-rods extendingupward from a secondary member, which is supported from below upon anadjusting-nut connected with the rod, so that the position of the centerof gravity of the bob and its secondary supporting member as a whole maybe varied with relation to the axis of the pendulum by means of theadjustable supports. Such adjustment, however,

will also vary the effective length of the pendulum, and to correct thevariations the secondary member may then be adjusted with relation tothe rod until thedesired result is attained. In order to facilitate thisfinal adjustment, the pendulum-rod is provided with a scale, so that byobserving the said scale before the compensating adjustment is made theother adjustment is easily made approximately by raising or lowering thesupporting mem- Serial No. 149,155- (No model.)

her until the bob stands at approximately its original position withrelation to the scale.

A further feature of the invention consists in a pivotal support for thependulum, which consists of a slotted block to receive a thin strip ofmetal, which extends into the slot and is held therein by a transversepin, the said block being screwed into the top of the woodenpendulum-rod, so that the said rod can be turned slightly in eitherdirection until the pendulum-bob swings parallel to the face of theclock and parallel to its own plane of oscillation.

The drawing is a perspective view, partly in section, of aclock-pendulum embodying the invention.

The pendulum-rod a, which is preferably of wood, is pivotally supported,as will be hereinafter described, and provided at its lower end with ascrew-threaded portion (4 adapted to receive an ad justing-nut a uponwhich the support for the pendulum-bob rests.

In accordance with the invention the pendulum-bob b, which is of amaterial different from that of the rod, being preferably of metal isdirectly supported by a member 6 and the part I) is provided with anopening through the. middle for the pendulum-rod a, so that it islongitudinally movable with relation to the rod. As herein shown, thesupporting member 6 is preferably L-shaped in crosssection, as shown, inorder that the front part may hide the screw portion of thependulum-rod, and thereby improve the appearance of the pendulum as awhole.

The bob Z) is shown as supported upon adjusting-nuts c screw-threadedupon vertical rods 0, which project upward from the supporting member 6and through openings Z) in the bob I), so that one of said parts may beadjusted with relation to the other by turning the nuts 0 thus producinga greater or less amount of effective expansion and contraction in thebob and its support as a whole, so that exactly the right conditions maybe secured to cause such expansion or contraction of the bob as willexactly compensate for that of the rod. The proper adjustment can bevery nearly determined by calculation; but after the parts are assembledsubstantially perfect adjustment can be subsequently attained byexperiment when the clock is subjected to variations in temperature. Itis obvious, however, that the adjustments for compensation will vary tosome extent the effective length of the pendulum by shifting theposition of the center of gravity of the bob with relation to thepivotal support or axis of the pendulum, and in order to correct thisthe bob and its support as a whole are adjustable with relation to therod by means of the nut a In order to facilitate this final adjustment,the rod is shown as provided with a scale a, so that by observing saidscale before the compensating adjustment is made the other adjustmentcan be approximately attained at once by turning the nut a until themember 5 of the bob is returned approximately to the position relativeto the scale from which it started.

As herein shown, the pendulum is provided with a novel fastening devicefor the pivotal support, the purpose of which is to easily arrange thependulum so that the bob, which is ordinarily comparatively thin, mayhang parallel to the plane of its oscillation and to the clock-case.

As herein shown, the pivotal supporting member consists of a block cl,provided with a screw (Z to enter the top of the pendulumrod 0, the saidblock d being provided with a slot (Z to receive a thin spring (2,supported at (Z the said spring being secured in the block by means of atransverse pin (Z With this construction it is obvious that thependulum-rod can be turned with relation to its support upon the screw(Z until it swings exactly parallel to the plane of its oscillation, asis desired.

It is not intended to limit the invention to the specific constructionand arrangement herein shown and described, since modifications may bemade without departing from the invention.

I claim- 1. A compensating pendulum comprising a pendulum-rod providedat its lower end with an adjusting-nut, a support for the pendulumbobresting upon said adjusting-nut, supporting-rods for said bob connectedwith said support, and adjusting-nuts upon said supportingrods to varythe position of the bob relative to its support.

2. A compensating pendulum comprising a pendulum-rod of wood provided atits lower end with an adj usting-nut, a pendulum-bob, a support for saidbob which in turn is supported upon said adjusting-nut and provided withvertical members which enter openings with which said pendulum-bob isprovided, adjusting-nuts upon said supporting members upon which nutssaid bob directly rests, and a scale upon the face of the pcndulum-rod,as set forth.

3. A pendulum comprising a wooden pendulum-rod, and a metalliccompensating bob; a slotted block, screw-threaded into the upper end ofsaid pendulum; a strip of thin metal secured to the clockwork-frame andprojecting into the slot in said block; and a transverse pin' to securesaid thin metal strip in said block.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JOHN W. DAILY.

Witnesses:

HENRY J. LIVERMORE, NANCY P. FORD.

